The present invention relates to a brush holder used for a motor and a manufacturing method of the brush holder.
A conventional brush holder is located inside a motor housing and includes a main body, which retains brushes, and a connector portion, which is integrally formed with the main body. The connector portion is exposed from the motor housing and is electrically connected to an external device. Terminals are embedded in the brush holder and extend from the connector portion to the main body of the brush holder.
The terminals include a first terminal, which receives power supply from the outside, and a second terminal, which sends out detection signals of a detector to the outside. The detector includes, for example, a rotation sensor, which detects rotational speed of the motor. The first and second terminals are apart from each other at a predetermined interval at the main body and the connector. In other words, the first and second terminals are insulated from each other.
The brush holder is formed of resin by injection molding. More specifically, resin is filled in a mold, with the first and second terminals placed in the mold, to form the brush holder.
In a case when the brush holder is molded with separate terminals placed in the mold, the procedure for placing the terminals in the mold is complicated. Therefore, in the conventional brush holder, a unit in which the terminals are coupled to each other at predetermined portions is placed in the mold. Then, resin is filled in the mold to form the brush holder. After that, the coupling portions between the terminals are cut.
The cut portions of the terminals are exposed from the brush holder. Therefore, liquid could enter from the exposed portion. Further, if any of the cut portions is in the vicinity of the brushes, foreign objects (such as brush powder scattered from the brushes) could enter from the exposed portion and cause a short-circuit at the cut portion of the terminals.